Electric discharge device



H. D. ARNOLD ELECTRIC DISCHARGE DEVICE Original Filed May 10 May 29,11923.

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@ontinnation of application Serial. No.

To all whom'it may concern:

Be it ,knowniothat I, HAnonowDn 'Fonnsrr ARNoLo, a citizen of the UnitedStates, residing at East Orange, in the county of Es- 5 sex and State ofNew Jersey, have mvented certain new and useful Improvements in ElectricDischarge Devices, of which the following is a full, clear, concise, andexact description.

This invention relates to electric discharge .devices and in-fparticular to an improved construction and arrangement of electrodesfor'the purpose of producing a large current output therefrom.

In designing devices of this type for large current output it issometimes essential among other things that the tube or vessel enclosingthe various electrode elements should be evacuated to as high a degreeas possible; a process which involves driving out any gases which may beoccluded by the various metallic surfaces within the tube. This can-bestbe done by heating the various electrode elements] by some 26 externalmeans during the process of evacuation. Where large electrode surfacesare em loyed the problem of heating them to a suffibient degree to driveout these occluded gases becomes a matter of some difliculty.

30 This is particularly true in the case of the anode or outputelectrode, which is customarily in the form of a plate and cannotreadily be heated by passing current through it owing to its lowresistance and the consequently high currents which would therefore benecessary.

This invention provides an output electrode which is made up of aplurality of bands or strips serially connected and there- 40 by capableof being heated by the passage of an electric current through itslength, thus making possible the heating of the anode during the processof evacuation without the employment of unduly high ourrents.

A further object of this invention is to provide a substantiallycontinuous anode surface composed of a plurality of serially connectedsections.

A further dificulty which has arisenin the design ofdevioes of the typein question is that where a filamentary cathode is employed and thelength of such cathode is increased for the purpose of obtaining astate, filed my to, new. rm application filed February 17, me. Serialno. 277,57t.

large" electron-emitting area, the potential dropin the filament, due tothe heating current therethrough, evelops a considerable difference ofpotential between the two ends of the filament so that when anelectromotive force is impressed between one end of the filament and theanode, for example, a greater difference of potential will exist betweenthe negative end of the filament and the anode than between the positiveend of the filament and the anode. This results in an unevendistribution of the space current over the surface of the cathode andanode and prevents the operation of the device as a whole at its maximumefficiency.

In the present invention this difliculty is largely overcome by leadingthe heating current into and out of the filament at a plurality ofpoints, whereby the filament is in efiect divided into a number ofsections connected in multiple with respect to the heating battery, andthe consequent difference in potential between any two sections of thefilament due to the drop therein is greatly diminished.

Ithas been found, however, when large electrodes are employed that theusual way of maintaining the positions of electrodes by a glass arborsupfported at one end of the contalner is not su cient to withstand thestrains to which the arbor is subjected. In accordance with thisinvention, the electrodes are'mounted on an insulating framework whichisso supported at both ends of the container that while allowing theframework to expand and contract under heat, it still prevents anysubstantial lateral vibration of the structure. One way this may beaccomplished is to have located at the upper end of the insulatingframework, which is the end hitherto unsupported, a projecting tip orarm preferably of insulating material that fits snugly in a constrictedportion or neck of the container.

Other features of this invention contributing to a high currentproduction will appear from a consideration of the accompanying drawing,which shows in fragmentary perspective form a thermionic amplifieremploying the features above mentioned. In the drawing, 3 is a metallicribbon which is folded back and forth in zigzag formation in a plane andsupported at its various folded assage of the anode being greater thanthe thickness thereof and the distance between the edges of adjacentstrips being small inqcomparison to the width of the strips, as clearlyshown in the drawings. In the case in question two of such anodeelements are employed, the ribbon 3'passing serially from one anodeelement to the other as at 7. The two endsof the ribbon 3 are connectedto leading-in wires 8, through which current can be passed to heat theribbon 3 to the necessarytemperature to drive out occluded gases.

As illustrated, the back framework 6 is supported at a definite distancefrom the framework 9 by means ofa supporting connection which in thedrawings is shown as forming a U-shaped continuation of the frameworks,the tip 30 being connected to this U-shaped portion. A similarsupporting connection is provided between the framework 9 and the frontframework 6. The frameworks and the electrodes supported thereby aremaintained at their proper relative distances near the squash 25 bymeans of the supporting connections between the lower ends of theseframeworks and the squash. The supporting connection provided at theouter ends of the frameworks aids in maintaining the electrodes properlypositioned.

Midway between the two glass frames 6 is a third glass frame 9 having anumber of supporting points 10 fused into its vertical legs andregularly spaced in such a manner that a filament 11 may be threadedback and forth thereon in the manner shown. A leading-in wire 12 isconnected to the filament 11 at points 13 and 14. Another leading-inwire 15 is connected to the filament at points 16 and 17 When a heatingbattery, (not shown) is connected between wires 12 and 15 current willpass through the filament, through three paths, one from point 13 topoint 16, another from point 13 to point 17 and still another from point14 to point 17. Thus, assuming a given current flow through any sectionof the filament, it is seen that the potential difference, due to thiscurrent flow, between any two points in the filament will not be morethan one-third the potential drop which'might obtain were the heatingcurrent to flow through the entire filament in series. It is obviousthat a greater uniformity of potential could be obtained by dividing thefilament into a greater number of sections.

A cage-like grid or input electrode surrounds the frame 9. and is formedof the vertical wires 20 and the horizontal wires 21 intense which'arewelded together at their points of intersection 22 or connected in anyother suitable manner. and the turns of wire are preferably of sub-.stantially the same size as shown, although this 1s not essential. Thecurved portions 21 of the gridturns extend beyond the rods forming theframe 9. Since the cage-like grid is a rigid construction which retainsits shape without additional support, the grid need not closelyembracethe frame 9 as shown. Between the bends 21 and the frame 9 arethe conductors 1 2 and 15 which connect the cathode sections inparallel.

Supporting connections such as 31 and 32 may be provided between thegrid and the framework 9.

The whole electrode-assembly is suitably mounted on the squash 25 whichis sealed 1nto the glass vessel 26 in the usual manner (not shown) andthe vessel thereupon exhausted and sealed at 27. Projecting from theframework 6 is a tip or arm 30, preferably of insulatin material, thatprojects lnto the constricte portion 27 in such a manner as to preventsubstantial lateral vibration of the framework 6 while still permittingthis framework to expand longitudinally. This tip 30 also serves as aguide for determining and fixing the position of the framework duringthe process of sealing the squash 25 to the vessel.

This application is a continuation of Arnold application No. 27,222,filed May 10, 1915, for thermionic amplifiers.

What is claimed is:

1. An electric discharge device comprising an anode composed of aplurality of parallel strips serially connected, the width of each ofsaid strips being greater than its thickness.

2. An electric discharge device comprising a cathode, an anode and anauxiliary electrode, said anode being composed of a plurality ofparallel strips lying in the same plan and connected in series, thedistance between the edges of adjacent strips being small in comparisonto the width of said strips.

3. An electric discharge device having a filamentary cathode composed of.a plurality of zigzag sections lying in the same plane and connected inparallel.

4. An anode surface for an electric discharge device comprising aplurality of serially connected sections so arranged that the distancebetween adjacent sections is small in comparison to thewidth of one ofsaid sections.

5. In an electric discharge device, a glass supporting frame, aplurality of supporting points thereon, a filamentary cathode supportedon said points in zigzag formation, a cage-like grid surrounding saidframe, a second supporting frame parallel to said The straight verticalwires first mentioned frame, and an anode supported thereon and composedof a plurality of parallel metal strips connected in series, said stripsbeing so arranged as to form a substantially continuous surface.

6. An electric discharge device comprising an evacuated vessel having asquash, a plurality of electrode supports independently supported at oneend from said squash and means connecting, the other ends of saidsupports to maintain said ends in fixed spaced relation.

7. An electric discharge device comprising an evacuated vessel having asquash, an anode, a cathode, a control electrode, a

framework on which said anode is mounted a second framework on whichanother of said electrodes is mounted, connections between saidframeworks and said squash, means remote from said squash for preventingrelative movement of said frameworks, and means for preventingsubstantial vibration of said frameworks within said vessel.

8. An electric discharge device comprising an evacuated vessel having asquash, an anode, a cathode, a control electrode, a framework on whichsaid anode is mounted, a second framework on Which another of saidelectrodes is mounted, connections between said frameworks and saidsquash, means remote from said squash for preventing relative movementof said frameworks, said vessel having a constricted portion, and an armextending from said frameworks into said constricted portion.

9. An electric discharge device compris-v ing a plurality of parallelelectrode surfaces, each comprising-a plurality of parallel strips, thedistance betweenthe edges of adjacent strips being small in comparisonto the width of said strips, a framework for each of said surfaces, andmeans for Q holding said frameworks apart.

10. In an electric discharge device, an electrode comprisingintersecting wires secured together at their inprsections forming aflattened cylinder. 1

11. A thermionic device comprising an anode, a cathode, a grid enclosingsaid cathode, said cathode extending laterally beyond the longitudinalcentre of said grid, and said grid comprising a plurality of turns,surrounding said cathode and a Wire crossing said turns and weldedthereto.

12. An electric discharge device, an electrode comprising aplurality ofrelatively widely spaced turns of wire, a plurality of supporting wiresintersecting said turns and secured thereto to maintain the spacedrelation between said turns.

13. An electric discharge device comprising an anode, a. cathode and agrid, said grid having turns surrounding said cathode, asupport for saidgrid and cathode comprising'a rod within said turns, said turnsextending beyond said rod, and means for supporting said grid by saidrod.

14. An electric discharge device comprising an anode, acathode and acage-like grid, a support comprising a rod with in said grid, a cathodesupported by said rod, said grid loosely embracing said rod, and asupporting connection between said rod and said grid.

15. An electric discharge device comprising a cathode having a pluralityof sections adapted to be connected in parallel, 'a grid having turnssurrounding said sections a rod adapted to support said turns but spacedtherefrom, a supporting connection between said rod and said grid, aconductor supported by said rod and connected to a plurality of saidsections, and a cooperating anode.

16. An electric discharge device comprising a cathode having avplurality of sections connected in parallel, a grid having turnssurrounding said sections, a pair of parallel rods adapted to supportsaid turns but spaced therefrom, a supportin connection between saidrods and said gri a plurality of parallel extending conductorsconnecting said sections in parallel, and a cooperative anode. '17. Inan electric discharge device, an electrode comprising a ribbon ofconducting material folded back and forth on itself to provide aplurality of sections of ribbon lying in a substantially plane surface.

In witness whereof, I hereunto subscribe my name this 7th day ofFebruary, A. D.

HAROLD-D. ARNOLD.

